特殊地形对鄂东北一次局地强降水过程的作用机制分析
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摘要
基于FNL1°×1°再分析资料和来自国家气象信息中心的区域自动站与CMORPH小时降水融合产品,通过高分辨率的WRF数值模拟,本文重点分析了2015年7月22-24日期间在西南涡东移过程中,受长江中下游特殊地形影响,在鄂东北江汉平原河谷地区诱发生成的一次短时局地强降水天气过程,围绕特殊地形对局地降水增幅的作用机制展开一系列的深入研究,研究结果表明:此次局地强降水过程是在长江中下游特殊的中尺度地形影响下,配合东移西南涡前部偏南暖湿气流的输送,两者共同作用而诱发产生,此次局地降水过程持续时间短,降水增幅显著。之后,通过研究单一地形对局地降水的影响发现,大别山脉作为单一地形的作用效果为提升局地降水增幅,扩大强降水范围;幕阜山脉作为单一地形的作用效果为削弱降水增幅,缩小强降水范围。进一步深入分析上述单一地形影响降水变化的作用机制得出,大别山脉的地形作用有利于局地强降水区附近对流层低层的层结对流不稳定性增强,以及降水区近地面层冷池的维持和增强,有利于提升局地降水的增幅。而与大别山脉对局地降水作用效果不同,就幕阜山脉单一地形而言,地形对偏南暖湿气流的阻挡作用,削弱了局地强降水期间进入降水区的水汽通量,继而对局地降水的增幅有抑制作用。此外通过研究组合地形对局地降水的影响时发现,大别山脉、幕阜山脉、皖南山地,以及幕阜山脉和皖南山地之间的狭窄河谷地形共同构成的类似"喇叭口"地形,其产生的狭管效应,使进入地形区内的偏南气流辐合加强,而幕阜山脉和大别山脉之间的河谷地区,作为偏南气流从幕阜山脉东侧绕流进入江汉平原的重要通道,有效保证了强降水区域内充足的正涡度平流输送,上述有利的地形组合配置对于局地降水发展增强起到了至关重要的作用。
Based on FNL reanalysis data and hourly precipitation data converted from both regional meteorological station and CMORPH and using the method of high resolution WRF numerical simulation, this paper analyzes a typical short-time local heavy rain process triggered by easterly mobile southwest vortex and complex terrain located in the northeast of Hubei in 22-24 July 2015. Further study is made on possible effect mechanism of how the mesoscale topography affects the increment of local rainfall. The result shows that the increment process of local rainfall was under the influence of the special topography in the middle-lower reaches of Yangtze River, coupled with the effect of transportation of moist air in the front of southwest vortex. The two items worked together, triggering the weather process. The duration of local rainfall was short, but the increment was obvious. By researching the effect mechanism of single terrain on the local rainfall, we found that the Dabie Mountain's terrain height impacted increment and scope of local severe rainfall positively,while the Mufu Mountain's terrain height influenced the increment and scope of local rainfall negatively. As for the effect of Dabie Mountain's terrain on the rainfall, the terrain was advantageous to reinforcement of convective instability, reinforcement of wind convergence and vertical shear, as well as maintenance and reinforcement of cold pool in lower troposphere. Different from Dabie Mountain's terrain,Mufu Mountain's terrain obstructed southerly moisture flow,then decreased the transportation of vapor flux above the rainfall area, which was unfavorable for increment of local rainfall.In addition, by researching the effect mechanism of the combined terrain on the local rainfall, we found the trumpet-shaped topography consisting of Dabie Mountain's terrain, Mufu Mountain's terrain, Wannan Mountain's terrain,and river valley between Mufu Mountain and Wannan Mountain, which forced the southerly airflow into terrain area to converge. What's more, the river valley between Mufu Mountain and Dabie Moutain acted as an important channel for the southerly airflow to flow back into the Jianghan Plain from the east of Mufu Mountain, which effectively guaranteed the positive vorticity advection to be transported into the heavy precipitation area. In a word, the above favorable terrain configuration resulted in the increment of local severe rainfall.
Based on FNL reanalysis data and hourly precipitation data converted from both regional meteorological station and CMORPH and using the method of high resolution WRF numerical simulation, this paper analyzes a typical short-time local heavy rain process triggered by easterly mobile southwest vortex and complex terrain located in the northeast of Hubei in 22-24 July 2015. Further study is made on possible effect mechanism of how the mesoscale topography affects the increment of local rainfall. The result shows that the increment process of local rainfall was under the influence of the special topography in the middle-lower reaches of Yangtze River, coupled with the effect of transportation of moist air in the front of southwest vortex. The two items worked together, triggering the weather process. The duration of local rainfall was short, but the increment was obvious. By researching the effect mechanism of single terrain on the local rainfall, we found that the Dabie Mountain's terrain height impacted increment and scope of local severe rainfall positively,while the Mufu Mountain's terrain height influenced the increment and scope of local rainfall negatively. As for the effect of Dabie Mountain's terrain on the rainfall, the terrain was advantageous to reinforcement of convective instability, reinforcement of wind convergence and vertical shear, as well as maintenance and reinforcement of cold pool in lower troposphere. Different from Dabie Mountain's terrain,Mufu Mountain's terrain obstructed southerly moisture flow,then decreased the transportation of vapor flux above the rainfall area, which was unfavorable for increment of local rainfall.In addition, by researching the effect mechanism of the combined terrain on the local rainfall, we found the trumpet-shaped topography consisting of Dabie Mountain's terrain, Mufu Mountain's terrain, Wannan Mountain's terrain,and river valley between Mufu Mountain and Wannan Mountain, which forced the southerly airflow into terrain area to converge. What's more, the river valley between Mufu Mountain and Dabie Moutain acted as an important channel for the southerly airflow to flow back into the Jianghan Plain from the east of Mufu Mountain, which effectively guaranteed the positive vorticity advection to be transported into the heavy precipitation area. In a word, the above favorable terrain configuration resulted in the increment of local severe rainfall.
引文
陈潜,赵鸣,2006.地形对降水影响的数值试验[J].气象科学,26(5):484-493.
崔春光,闵爱荣,胡伯威,2002.中尺度地形对“98.7”鄂东特大暴雨的动力作用[J].气象学报,60(5):602-612.
冯强,叶汝杰,王昂生,等,2004.中尺度地形对暴雨降水影响的数值模拟研究[J].中国农业气象,25(4):1-4.
傅抱璞,1992.地形和海拔高度对降水的影响[J].地理学报,47(4):302-314.
郭蕊,2012.长江流域、淮河流域梅雨期暴雨地形敏感性试验对比研究[D].南京:南京信息工程大学.
李博,刘黎平,赵思雄,等,2013.局地低矮地形对华南暴雨影响的数值试验[J].高原气象,32(6):1638-1650.
刘建文,郭虎,李耀东,等,2005.天气分析预报物理量计算基础[M].北京:气象出版社:3-9.
刘璐,冉令坤,周玉淑,等,2015.北京“7.21”暴雨的不稳定性及其触发机制分析[J].大气科学,39(3):583-595.
盛春岩,高守亭,史玉光,2012.地形对门头沟一次大暴雨动力作用的数值研究[J].气象学报,70(1):65-77.
盛春岩,李建华,范苏丹,2014.地形及下垫面对渤海大风影响的数值
孙健,赵平,周秀骥,2002.一次华南暴雨的中尺度结构及复杂地形的影响[J].气象学报,60(3):333-342.
王靖羽,崔春光,王晓芳等,2014.2012年7月21日北京特大暴雨过程的水汽输送特征[J].气象,40(2):133-145.
王宛亭,2003.中国中东部地区地形谱解析及大气重力波拖曳[D].南京:南京大学.
王宗敏,丁一汇,张迎新,等,2014.副高外围对流雨带中的对流-对称不稳定及锋生的诊断分析[J].大气科学,38(1):133-145.
吴翠红,王晓玲,龙利民,等,2013.近10a湖北省强降水时空分布特征与主要天气概念模型[J].暴雨灾害,32(2):113-119.
吴涛,张家国,牛奔,2017.一次强降水过程涡旋状MCS结构特征及成因初步分析[J].气象,43(5):540-551.
徐昕,王其伟,王元,2010.迎风坡降水对中国东南地区降水贡献的估测[J].南京大学学报(自然科学),46(6):625-630.
杨金杨,冯志娴,王东勇,等,1991.中尺度地形对强对流天气的影响的数值诊断[J].气象学报,49(3):375-381.
叶笃正,1956.小地形对于气流的影响[J].气象学报,27(3):243-262.
尹宜舟,沈新勇,李焕连,2009.“07.7”淮河流域梅雨锋暴雨的地形敏感性试验[J].高原气象,28(5):1085-1094.
臧增亮,张铭,沈洪卫,等,2004.江淮地区中尺度地形对一次梅雨锋暴雨的敏感性试验[J].气象科学,24(1):26-34.
张家国,周金莲,谌伟,等,2015.大别山西侧极端降水中尺度对流系统结构与传播特征[J].气象学报,73(2):291-304.
赵玉春,王叶红,崔春光,2011.大对流有效位能和条件不稳定下地形降水的三维理想数值研究[J].气象学报,69(5):782-798.
郑婧,孙素琴,吴静,2014.梅雨锋短时大暴雨的多尺度环境场分析[J].气象,40(5):570-579.
周长艳,唐信英,邓彪,2015.一次四川特大暴雨灾害降水特征及水汽来源分析[J].高原气象,34(6):1636-1647.
朱素行,徐海明,徐蜜蜜,2010.亚洲季风区中尺度地形降水结构及分布特征[J].大气科学,34(1):71-82.
Bougeault P,Benech P,Bessemoulin P,et al,1997.PYREX:a summary of findings[J].Bull Amer Meteor Soc,78(4):637-650.
Bougeault P,Binder P,Buzzi A,et al,2001.The MAP special observing period[J].Bull Amer Meteor Soc,82(3):433-462.
Gleeson,1951.On the theory of cross-valley winds arising from differential heating of the slopes[J].J Meteor,8:309-405.
Grubisic V,Doyle J D,Kuettner J,et al,2004.T-REX Terrain-induced rotor experiment scientific overview document and experiment design 2004.https://www.researchgate.net/publication/235142086_The_Terrain-Induced_Rotor_Experiment_T-REX?ev=auth_pub.
Grubisic V,Lewis J M,2004.Sierra wave project revisited 50 years later[J].Bull Amer Meteor Soc,85(8):1127-1142.
Prandtl,1952.Essentials of fluid dynamics[M].Blackie and Son Ltd,London.
Whiteman C David,2000.Mountain Meteorology:Fundamentals and Applications[M].New York:Oxford University Press:355.
崔春光,闵爱荣,胡伯威,2002.中尺度地形对“98.7”鄂东特大暴雨的动力作用[J].气象学报,60(5):602-612.
冯强,叶汝杰,王昂生,等,2004.中尺度地形对暴雨降水影响的数值模拟研究[J].中国农业气象,25(4):1-4.
傅抱璞,1992.地形和海拔高度对降水的影响[J].地理学报,47(4):302-314.
郭蕊,2012.长江流域、淮河流域梅雨期暴雨地形敏感性试验对比研究[D].南京:南京信息工程大学.
李博,刘黎平,赵思雄,等,2013.局地低矮地形对华南暴雨影响的数值试验[J].高原气象,32(6):1638-1650.
刘建文,郭虎,李耀东,等,2005.天气分析预报物理量计算基础[M].北京:气象出版社:3-9.
刘璐,冉令坤,周玉淑,等,2015.北京“7.21”暴雨的不稳定性及其触发机制分析[J].大气科学,39(3):583-595.
盛春岩,高守亭,史玉光,2012.地形对门头沟一次大暴雨动力作用的数值研究[J].气象学报,70(1):65-77.
盛春岩,李建华,范苏丹,2014.地形及下垫面对渤海大风影响的数值
孙健,赵平,周秀骥,2002.一次华南暴雨的中尺度结构及复杂地形的影响[J].气象学报,60(3):333-342.
王靖羽,崔春光,王晓芳等,2014.2012年7月21日北京特大暴雨过程的水汽输送特征[J].气象,40(2):133-145.
王宛亭,2003.中国中东部地区地形谱解析及大气重力波拖曳[D].南京:南京大学.
王宗敏,丁一汇,张迎新,等,2014.副高外围对流雨带中的对流-对称不稳定及锋生的诊断分析[J].大气科学,38(1):133-145.
吴翠红,王晓玲,龙利民,等,2013.近10a湖北省强降水时空分布特征与主要天气概念模型[J].暴雨灾害,32(2):113-119.
吴涛,张家国,牛奔,2017.一次强降水过程涡旋状MCS结构特征及成因初步分析[J].气象,43(5):540-551.
徐昕,王其伟,王元,2010.迎风坡降水对中国东南地区降水贡献的估测[J].南京大学学报(自然科学),46(6):625-630.
杨金杨,冯志娴,王东勇,等,1991.中尺度地形对强对流天气的影响的数值诊断[J].气象学报,49(3):375-381.
叶笃正,1956.小地形对于气流的影响[J].气象学报,27(3):243-262.
尹宜舟,沈新勇,李焕连,2009.“07.7”淮河流域梅雨锋暴雨的地形敏感性试验[J].高原气象,28(5):1085-1094.
臧增亮,张铭,沈洪卫,等,2004.江淮地区中尺度地形对一次梅雨锋暴雨的敏感性试验[J].气象科学,24(1):26-34.
张家国,周金莲,谌伟,等,2015.大别山西侧极端降水中尺度对流系统结构与传播特征[J].气象学报,73(2):291-304.
赵玉春,王叶红,崔春光,2011.大对流有效位能和条件不稳定下地形降水的三维理想数值研究[J].气象学报,69(5):782-798.
郑婧,孙素琴,吴静,2014.梅雨锋短时大暴雨的多尺度环境场分析[J].气象,40(5):570-579.
周长艳,唐信英,邓彪,2015.一次四川特大暴雨灾害降水特征及水汽来源分析[J].高原气象,34(6):1636-1647.
朱素行,徐海明,徐蜜蜜,2010.亚洲季风区中尺度地形降水结构及分布特征[J].大气科学,34(1):71-82.
Bougeault P,Benech P,Bessemoulin P,et al,1997.PYREX:a summary of findings[J].Bull Amer Meteor Soc,78(4):637-650.
Bougeault P,Binder P,Buzzi A,et al,2001.The MAP special observing period[J].Bull Amer Meteor Soc,82(3):433-462.
Gleeson,1951.On the theory of cross-valley winds arising from differential heating of the slopes[J].J Meteor,8:309-405.
Grubisic V,Doyle J D,Kuettner J,et al,2004.T-REX Terrain-induced rotor experiment scientific overview document and experiment design 2004.https://www.researchgate.net/publication/235142086_The_Terrain-Induced_Rotor_Experiment_T-REX?ev=auth_pub.
Grubisic V,Lewis J M,2004.Sierra wave project revisited 50 years later[J].Bull Amer Meteor Soc,85(8):1127-1142.
Prandtl,1952.Essentials of fluid dynamics[M].Blackie and Son Ltd,London.
Whiteman C David,2000.Mountain Meteorology:Fundamentals and Applications[M].New York:Oxford University Press:355.